Friction draft gear



'April- 12,1932. E. H. SCHMIDT FRICTION DRAFT GEAR Filed July 24, 192e 3sheets-sheet 1 April 12, l1932. E, H. SCHMIDT FRICTION DRAFT GEAR FiledJuly 24. 1926 5 Sheets-Sheet 2 April 12, 1932. E. H. SCHMIDT FRICTIONDRAFT GEAR Filed July 24, 192e Svsheets-sheet 5 other features which Ishall hereinafter de'-A Patented Apr. 12, 1932 UNITED STATES PATENT 1EENEsT H. SCHMIDT, OECIQEVELANDEEIGHTS, oHIo, AssIGNoE To vNATIONALMAE-t LEAELE AND STEEL CAsTINGs COMPANY, 0E CLEVELAND, oHIo, ACoEPoEATIoN 0E oHIo Y Application meay July 24,

with the friction wedge and one of the shoes r removed; Fig. 6 is avperspective of the frlction shellpartly broken away Fig.' 7 is aperspective of one of the friction shoes; Fig. i 8 is a front elevation.of the frictionrshell,

plan of the friction shell,part 4 f and the lugsformed on'theV frictionshoe.

and Fig. 9 is a ly in section.

My inventionrelates to friction draft gear and comprises africtionbarrel or shell engaged bya pluralityof friction shoes and containingmeans for-causing the shoes dur-v ing compression or release to `rotateor'have an angular movementrelative to the longitudinal axis of theshell andthereby increase vthe frictional resistance, and distribute"the wear more uniformly withinthe friction casing. My invention alsocomprises various scribe rand claim. f

Referring tothe drawings, A indicates a spring caseor shell having'atits forward end outwardly extending flanges 2, which are engaged bycorresponding flanges 3 on the friction case or shell B. The flanges 2fand 3 are held together` by rivets 4,-the` headsl of which are madeflush with the flange 2',f asis' indicated at 5 in Fig. 1. At itsrearend the spring case A is provided with wings 6 suitably reinforced withribs 7 merging intothe sides of the case A. Y Y

Within the friction chamber B are friction shoesS interposed between thespringV seat 9 and thefriction wedge 1 0. ,The spring case A carries oneor more draft springs. 11 which Y bear at one end against the springseat 9 and at the other end against the base 12 of the spring case A.` Asmall release spring 13 is also interposed between the spring seat 9 andthe/frictionV wedge 10. The parts are held in assembled relation by theretaining rod 14, which has a bearing on Vthe wedgerl() andbase 12. l

The inside face lrvofthefriction case` or shell B may, if desired,.beytapered inwardly toward its rear end, and is preferably pro` EEICT'IONDEAET f GEA'E Y192e. `serial No. v124,560.-

vided with a'compression lug 16 and a pair. i

ofrelease lugs 17.` Cooperating with such inside face 15 and the lugs 16-and 17 are theV friction shoes 8. These shoes 8are 'formed v withspirally shaped faces 18 which cooperate with the spiral faces 19 on thelug 16, and' witha groove 20 cooperating with the spiral faces 21A-Onarelease lug 17. While in the construction shown, vthe groove is shown inthe lfriction shoe cooperable with lugs on the, friction shell, itis tobe understood that the' grooves may, if desired, be located n the shellv forward face'24 'of the spring'seat9, as is shown in Fig, 3. The face24'maybe of conicalor any desired shape. The shoes 8 arel /7' furtherprovided with wedging surfaces 25"; and 26, which engage thecorrespondingly inclined wedging surfaces 27 and 28 of the fric-Av tionwedge 10.

The operation of'my improved gear is as, follows: A When the gearisbeing compressed thefriction wedge 10 is forced rearwardly with respectto the friction shell B,`and` this in turn moves the shoes rearwardlyagainst the ac- 86 tion of the springs 11and against thefric tionbetween the surfaces 22 of the shoes and the inner face 15 of. the shellB. As the shoes [8 move rearwardly, the spiral surfaces 19-on the lug16cause theshoes 8 to rotate in opposite directions, dueto the guidingcontact with the faces 18 of the shoes 8,. This causes an additionalfrictionalengagement between the lug 16 of theshell and the face 18 onthe shoes. Further frictional resistance is also-v caused between therear surfaces 23'of the 'shoes andthe forward face 24 of the spring seat9 by the rotation of the shoes. The shoes thus have five frictionsurfaces, 18,y 22, 23, 25

and 26, which engage corresponding surfaces yon the'friction shell,wedge andspring seat. It will be seen that theprotation of the shoes inopposite directions serves to equalize the torsional forces andeliminates any tendency ofthe gear to rotate as a unit. u i Y As thepressure abates the release spring 13, if used, causes a slight outwardmovement of the wedge. The spring or springs 11 then move the springseat 9 and with it the shoes outwardly in a straight line until asurface in the groove 2O inthe shoe engages a surface of the releasinglug 17. During their initial releasing movement, the shoes do not rotatebecause of the clearance between the groove and the lug- 17, so as toprevent friction and thus provide an easy release.V After this initialreleasing action has taken place, the frictional adhesion between theparts is broken anl the spring 11 easily restores the parts to theirnormal position. The release lugs 17 also serve to rotate the shoes inreverse direction, causing them to assume their initial position.

A further result of the clearance between the groove y20 in the shoesand the lug 17 is to allow the shoes when the gear is again compressedto move inwardly in a straight line, until the shoes contact thespiralsurfaces 19. If desired, the clearance between one of the shoesand its guiding spiral may be made .greater than that between the othershoe and` its guiding spiral, thus causing one shoe to start rotationaheadof the other both during compression and release, and while theother is still moving in a straight line. The result of this is agraduated resistance during compression land a serial release.

The additional clearance also is of a further advantage in distributingthe lines of wear,

thus giving a somewhat smoother surface than would result from constanttravel of theV shoes back and forth along the same line.

One advantage in constructing the friction barrel separate from thespring case is that they may be made of different materials. Thus, forinstance, the friction chamber may be made of wear resista-nt steel, andthe spring case of malleable iron.

The terms and expressions which I have.

1. In a friction shock absorbing mechanism, a friction shell; frictionshoes disposed in said shell in frictional engagement therewith; wedgefor moving said shoes longitudinally of said shell; and means arrangedabout the circumference of said shell for rotating the shoes in oppositedirections about the longitudinal axis of said shell, said ro-Vtativemeans being effective during only a poi-tion of the compressionand release movements of the gear.

2. A friction shock absorbing mechanism comprising a friction shellhaving longitudition shoes; a wedge having a conicalwedging surface forengagement with said friction shoes to maintain them in frictionalengagement with said shell; yieldable means for resisting movement ofthe shoes longitudinally of' the-shell; and means arranged `about thecircumference of said shell for rotating the shoes with respectto thewedge. 4:. A friction shock absorbing mechanism comprising a frictionshell; friction shoes;

a central wedge member arranged to mainf `tain the friction shoes infrictional engagenient with said shell and to move them longitudinallywith` respect thereto upon conipression of the mechanism; yieldablemeans for resisting said movement of the shoes and guiding means on theshell for causing rotative movement of the shoes, the longitudinalmovement of each shoe being in the same direction and the rotativemovement of therr shoes being in opposite dircetions.

5. In a friction shock absorbing mechanism, a friction shell, frictionshoes disposed in said shell in frictional engagement therewith, a wedgearranged to move the shoes iii the same longitudinal direction relativeto the shell, yieldable means for resisting said movement of the shoes,and means arranged about the circumference of the shell and in fixedrelation thereto for rotating the shoes in opposite directions about thelongitudinal axis of said shell.

6. A shock absorbing mechanism comprising a friction casing, frictionshoes therein, a' wedge maintaining said friction shoes in frictionalengagement with the casing, the contiguous surfaces of said casing andshoes having cooperating spiral ribs and grooves for causing the shoesto rotate with respect to the wedge as they move longitudinally with it,and a compression spring arranged to oppose the longitudinal movement ofthe shoes.

7. A friction shock absorbing mechanism comprising a friction casing,friction shoes the casing having circumferential friction faces engagedby corresponding arc-shaped faces on the shoes, each shoe havingadjacent its arc-shaped face at a distance from the edges thereof aspiral friction surface cooperating with a. corresponding spiralfriction surface on the casing for rotating said shoe, a wedge formaintaining the friction shoes in frictional engagement with the casing,and for moving them longitudinally relative to it, and a compressionspring arranged to oppose the longitudinal movement Y of the shoes. Y 'Y8. In a shock absorber structure, a hollow friction member, frictionshoe members having frictional engagement with the inner surface of thehollovv friction member, interengaging spiral lugs and grooves on thecontiguous surfaces of said hollow friction member and said frictionshoe members, and a Wedging ,member having telescopic relation to saidfriction shoe members and arranged under pressure of the load to forcesaid friction shoe members radially outward to exert pressure againstthe surfaces of the hollow friction member with Which'they are inContact. 4 Y

ERNEST H. SCHMIDT.`

